The project involves a comparative study of wild type and crib-1, a cold-sensitive, ribosome biosynthesis mutant of Neurospora crassa, with an aim towards characterizing the biochemical defects of the mutant strain. Previous work has shown that at 10 degrees C, crib-1 synthesizes a disproportionate amount of 60S and 37S ribosomal subunits. As background for this work the kinetics of synthesis of the high-molecular-weight ribosomal DNAs (rRNAs) has been examined, and a model proposed for this scheme. Preliminary work has shown that this processing scheme is defective in crib-1 at 10 C. The following experiments constitute the project: (1) Examination of the kinetics of rRNA synthesis in crib-1 at 10 C to confirm the preliminary results. Further experiments will investigate the basis of the processing defect. 2) Ribosomal proteins from 60S an 37S ribosomal subunits of wild type and crib-1 will be compared using two-dimensonal polyacrylamide gel electrophoresis. 3) The methylatton of 25S and 17S rRNA isolated from wild type and crib-1 polysomes labelled to steady state with (C3H3) methionine will be compared. Total methylation will be calculated for each RNA and if there are differences between the strains the proportion of 2'-0-ribose- and base-methylation will be examined by alkaline hydrolysis of the RNAs followed by DEAE-cellulose column chromatography. Depending on the results, fingerprinting of the RNAs may be attempted to further characterize methylation differences.